Precision Approach Availability and Integrity Protection Limits

Karen Van Dyke, Quyen Hua, Stephen Rowson, Mitch Sams

Abstract:	An aircraft landing system must not only meet certain accuracy requirements, it must also achieve the necessary levels of integrity, availability, and continuity of function. Integrity is a measure of the probability that the system will not provide the user with hazardously misleading information. Continuity of function is a type of availability which is a measure of the probability that the system will remain available throughout a precision approach, assuming the system was available at the start of the approach. The design of a landing system requires a compromise between integrity and availability. A local-area availability model (LAAM) has been developed based on the local-area augmentation system (LAAS) architecture being worked on within RTCA SC- 159 Working Group 4. LAAM is a useful tool for determining availability of LAAS for CAT I, II, and III precision approach, as well as measuring the improvement in availability with such augmentations as pseudolites and geostationary satellites. Since the vertical and horizontal position error statistics are a function of satellite position (due to geometry and the effects of elevation angle on noise and multipath), integrity, availability and continuity of function can only be accurately estimated using a 24-hour simulation based on LAAM.
Published in:	Proceedings of the 53rd Annual Meeting of The Institute of Navigation (1997) June 30 - 2, 1997 Albuquerque, NM
Pages:	683 - 689
Cite this article:	Van Dyke, Karen, Hua, Quyen, Rowson, Stephen, Sams, Mitch, "Precision Approach Availability and Integrity Protection Limits," Proceedings of the 53rd Annual Meeting of The Institute of Navigation (1997), Albuquerque, NM, June 1997, pp. 683-689.
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